In general, a conventional turning drive apparatus used to turn a turret of a tank model transmits rotation of a motor as a drive source to an internal gear in the turret through a gear train. However, even if a tank model has a turret turning drive apparatus assembled therein, a user sometimes tries manually turning the turret. In this case, the turret cannot be easily turned due to a resistance of the turning drive apparatus, and when the turret is forcibly turned, there is a possibility that the gear train and the like are damaged.
To cope with the above problem, there is provided a turning drive apparatus in which the tooth profile of a drive gear meshed with an internal gear disposed in a turret is formed in a small size so that a tooth slip occurs between the internal gear and the drive gear meshed therewith when a user manually turns the turret to reduce a resistance when the turret is manually turned as well as protect the turning drive apparatus from an excessive torque.